The present invention relates generally to high frequency resonant DC--DC converters, and more particularly, to an improved voltage variable capacitor or varactor for use in regulating such high frequency resonant DC--DC converters.
The assignee of the present invention has heretofore developed a high frequency DC--DC converter to meet the demanding cost and performance requirements of high power, high frequency electronic systems such as active arrays and high speed processors. One such high frequency DC--DC converter is disclosed in U.S. Pat. No. 5,410,276, entitled "RP modulation using a pulsed DC power supply", assigned to the assignee of the present invention
The concepts presented in U.S. Pat. No. 5,410,276 were improved upon in U.S. Pat. No. 5,708,573 entitled "Varactor controlled fixed frequency VHF DC--DC converter". In the VHF DC--DC converter disclosed in this patent, the variable capacitance for regulation is created using a semiconductor varactor diode that is reverse-biased to create a variable "capacitor". This device must remain reverse-biased to remain functional in the circuit and to give a 2:1 change of capacitance.
In this converter, the semiconductor varactor diode must be reverse-biased to at least 70 volts, and as high as 100 volts, to remain a variable capacitor in the circuit. This high voltage control bias results in the need for an expensive Application Specific Integrated Circuit (ASIC), and additional circuitry in the DC--DC converter. The use of the high voltage biased varactor semiconductor diode results in increased cost and size of the DC--DC converter.
It would therefore be desirable to regulate a power converter in a manner that decreases circuit complexity, cost, weight and improves the performance thereof. Accordingly, it is an objective of the present invention to provide for an improved voltage variable capacitor or varactor for use in he regulation of high frequency resonant DC--DC converters.